Recently, vehicles are manufactured based on studies conducted to secure driving force using internal combustion engines and/or electric motors, in order to reduce air pollution from exhaust gas of vehicles. Accordingly, the vehicles have evolved in the order of hybrid vehicles, plug-in hybrid vehicles and electric vehicles. In this case, the hybrid vehicles and plug-in hybrid vehicles have an internal combustion engine, an electric motor and a battery pack, and the electric vehicles have an electric motor and a battery pack, but not an internal combustion engine.
Accordingly, the battery pack has evolved together with hybrid vehicles, plug-in hybrid vehicles and electric vehicles. The battery pack is configured to be chargeable from outside an electric vehicle. The battery pack has a pack case and a battery module, and the pack case comprises a lower case and an upper case, thereby encasing the battery module. The battery module has battery cells and cartridges. The cartridge is configured to accommodate one or more battery cells. Here, the battery module is configured to secure the cartridges physically into one configuration.
The battery module has one or more auxiliary components to secure the cartridges. In order to realize the battery pack, the battery module is screw-coupled to the lower case using the auxiliary component. In this case, the coupling of the battery module and the lower case increases the number of components of the battery pack and increases the volume of the battery pack. Therefore, numerous studies to minimize the number of components of the battery pack and to reduce the volume of the battery pack are being conducted. One example of the studies was disclosed in the ‘battery pack’ of EP 2 328 205 B1 (granted date; Jul. 17, 2013).
A plurality of such battery packs are accommodated in a housing, thereby forming a battery pack module together with the housing. The battery pack includes batteries and a case. The case accommodates the batteries. Here, the case has sliding ribs at both side portions. The battery pack is inserted into a slot of the housing using the sliding ribs of the case. Since the case is not screw-coupled to the housing, it does not increase the number of components of the battery pack module.
However, since the housing has a flat outer circumferential surface and a bent inner circumferential surface, and has a different thickness per location along the inner surface, when the housing repeatedly receives external force through the outer circumferential surface, the housing is repeatedly bent and unbent by the effect of the external force, and is thus permanently crushed or broken later on. Deformation of the initial shape of the housing makes it difficult to accommodate the cases and/or batteries through the housing with stability.
Further, since the battery pack module is configured to secure the battery packs into one configuration through bus bars, when the housing receives external force, the battery packs deliver the external force to the cases and the batteries at the same time having the cases and the batteries in one bundle. Therefore, affected by the external force, the cases and the batteries have a uniform stress in most of the battery packs. The stress causes deformation in the cases and/or batteries during the life expectancy of use of the battery packs. The deformation of the cases and/or batteries shortens the life expectancy of use of the battery packs.